On the evolution of the resonant planetary system HD128311

A significant number of the known multiple exoplanetary systems are containing a pair of giant planets engaged in a low order mean motion resonance. Such a resonant condition protects the dynamics of these planets resulting in very stable orbits. According to recent studies the capture into a resonance is the result of a planetary migration process induced by the interaction of the planets with a protoplanetary disk. If the migration is slow enough (adiabatic) next to a mean motion resonance, the two planets will also be in apsidal corotation. The recently refined orbital parameters of the system HD 128311 suggest that the two giant planets are in a 2:1 mean motion resonance, however without exhibiting apsidal corotation. Thus the evolution of this system can not be described by an adiabatic migration process alone. We present possible evolution scenarios of this system combining migration processes and sudden perturbations. We model migration scenarios through numerical integration of the gravitational N-body problem with additional non-conservative forces. Planet-planet scattering has been investigated by N-body simulations. We show that the present dynamical state of the system HD128311 may be explained by such evolutionary processes.Comment: 4 Pages, 7 Figures, accepted for AA Letter

Multinomial discrete choice models (in Russian)

This essay briefly describes the main features of some well-known multinomial discrete choice models: the standard logit, the mixed logit, and the probit.

On the Finite Sample Properties of Conditional Empirical Likelihood Estimators

We provide Monte Carlo evidence on the finite-sample behavior of the conditional empirical likelihood (CEL) estimator of Kitamura, Tripathi, and Ahn and the conditional Euclidean empirical likelihood (CEEL) estimator of Antoine, Bonnal, and Renault in the context of a heteroscedastic linear model with an endogenous regressor. We compare these estimators with three heteroscedasticity-consistent instrument-based estimators and the Donald, Imbens, and Newey estimator in terms of various performance measures. Our results suggest that the CEL and CEEL with fixed bandwidths may suffer from the no-moment problem, similarly to the unconditional generalized empirical likelihood estimators studied by Guggenberger. We also study the CEL and CEEL estimators with automatic bandwidths selected through cross-validation. We do not find evidence that these suffer from the no-moment problem. When the instruments are weak, we find CEL and CEEL to have finite-sample properties—in terms of mean squared error and coverage probability of confidence intervals—poorer than the heteroscedasticity-consistent Fuller (HFUL) estimator. In the strong instruments case, the CEL and CEEL estimators with automatic bandwidths tend to outperform HFUL in terms of mean squared error, while the reverse holds in terms of the coverage probability, although the differences in numerical performance are rather small

Nonsequential Search Equilibrium with Search Cost Heterogeneity

We generalize the model of Burdett and Judd (1983) to the case where an arbitrary finite number of firms sells a homogeneous good to buyers who have heterogeneous search costs. We show that a price dispersed symmetric Nash equilibrium always exists. Numerical results show that the behavior of prices with respect to the number of firms hinges upon the shape of the search cost distribution: when search costs are relatively concentrated (dispersed), entry of firms leads to higher (lower) average prices.nonsequential search, oligopoly, arbitrary search cost distributions

On the Identification of the Costs of Simultaneous Search

This paper studies the identification of the costs of simultaneous search in a class of (portfolio) problems studied by Chade and Smith (2006). We show that aggregate data from a single market, or disaggregate data from a single market segment, do not provide sufficient information to identify the costs of simultaneous search in any reasonable interval. We then show that by pooling aggregate data from multiple markets, or disaggregate data from multiple market segments, the econometrician can identify the costs of simultaneous search in a non-empty interval. Within the context of specific examples, we illustrate that identification of the search cost distribution in its full support may easily be obtained.search costs, portfolio choice, non-parametric identification

The effect of childhood obesity on social welfare

The young generation is the most influenced and vulnerable segment of the market. Food with high level of fat, sugar and/or salt are popularised for this segment. At the same time nearly 7 people die of obesity or from complications of obesity in Hungary each hour - one every 9 minutes. Approximately 119 million Americans, or 64.5 percent, of adult Americans are either overweight or obese. 17.5 million obese young persons live in the European Union. The result is the drastic elevation of the hygienic expenses. The average health care cost of overweight persons is higher by 42% than normal bodyweight ones. Per capita spending on fast foods is unbelievable and rising. The value of average spending was 2.5 € in 2002. Fast food sales continue to boom despite warnings about obesity. The consumption of these products can contribute to the increased level of childhood obesity. 12.0% of young person’s visited a fast food restaurant at least with a weekly regularity. The value is 16.9% in case of young men higher than in case of young ladies (8.1%) to our research. We can state the respondents underestimate the costs of fast foods.fast food, childhood obesity, cost, youth, Agricultural and Food Policy, Food Consumption/Nutrition/Food Safety, Food Security and Poverty, Health Economics and Policy, Marketing,

VLBI observations of a flared optical quasar CGRaBS J0809+5341

A bright optical flare was detected in the high-redshift ($z=2.133$) quasar CGRaBS J0809+5341 on 2014 April 13. The absolute magnitude of the object reached $-30.0$ during the flare, making it the brightest one (in flaring stage) among all known quasars so far. The 15 GHz flux density of CGRaBS J0809+5341 monitored in the period from 2008 to 2016 also reached its peak at the same time. To reveal any structural change possibly associated with the flare in the innermost radio structure of the quasar, we conducted a pilot very long baseline interferometry (VLBI) observation of CGRaBS J0809+5341 using the European VLBI Network (EVN) at 5 GHz on 2014 November 18, about seven months after the prominent optical flare. Three epochs of follow-up KaVA (Korean VLBI Network and VLBI Exploration of Radio Astrometry Array) observations were carried out at 22 and 43 GHz frequencies from 2015 February 25 to June 4, with the intention of exploring a possibly emerging new radio jet component associated with the optical flare. However, these high-resolution VLBI observations revealed only the milliarcsecond-scale compact "core" that was known in the quasar from earlier VLBI images, and showed no sign of any extended jet structure. Neither the size, nor the flux density of the "core" changed considerably after the flare according to our VLBI monitoring. The results suggest that any putative radio ejecta associated with the major optical and radio flare could not yet be separated from the "core" component, or the newly-born jet was short-lived.Comment: 4 figures, 2 tables, accepted for publication in PAS

Simultaneous search for differentiated products:The impact of search costs and firm prominence

We extend the literature on simultaneous search by allowing for differentiated products and search cost heterogeneity. We show conditions under which a symmetric price equilibrium exists. We provide a necessary and sufficient condition under which an increase in search costs may result in a lower, equal or higher equilibrium price. We extend this analysis to the case with more than two firms. The effects of prominence on equilibrium prices are also studied. The prominent firm charges a higher price than the non-prominent firm and both their prices are below the symmetric equilibrium price. Consequently, market prominence increases the consumers’ surplus